Spectral, thermal, molecular modeling and biological studies on mono- and binuclear complexes derived from oxalo bis(2,3-butanedionehydrazone)

Abstract

BackgroundHydrazones and their metal complexes were heavily studied due to their pharmacological applications such as antimicrobial, anticonvulsant analgesic, anti-inflammatory and anti-cancer agents. This work aims to synthesize and characterize novel complexes of VO2+, Co2+, Ni2+, Cu2+, Zn2+, Zr4+and Pd2+ ions with oxalo bis(2,3-butanedione-hydrazone). Single crystals of the ligand have been grown and analyzed.ResultsOxalo bis(2,3-butanedionehydrazone) [OBH] has a monoclinic crystal with P 1 21/n 1 space group. The VO2+, Co2+, Ni2+, Cu2+, Zn2+, Zr4+ and Pd2+ complexes have the formulas: [VO(OBH–H)2]·H2O, [Co(OBH)2Cl]Cl·½EtOH, [Ni2(OBH)Cl4]·H2O·EtOH, [Cu(OBH)2Cl2]·2H2O, [Zn(OBH–H)2], [Zr(OBH)Cl4]·2H2O, and [Pd2(OBH)(H2O)2Cl4]·2H2O. All complexes are nonelectrolytes except [Co(OBH)2Cl]Cl·½EtOH. OBH ligates as: neutral tetradentate (NNOO) in the Ni2+ and Pd2+ complexes; neutral bidentate (OO) in [Co(OBH)2Cl]Cl·½EtOH, [Zr(OBH)Cl4]·2H2O and [Cu(OBH)2Cl2]·2H2O and monobasic bidentate (OO) in the Zn2+ and VO2+ complexes. The NMR (1H and 13C) spectra support these data. The results proved a tetrahedral for the Zn2+ complex; square-planar for Pd2+; mixed stereochemistry for Ni2+; square-pyramid for Co2+ and VO2+ and octahedral for Cu2+ and Zr4+ complexes. The TGA revealed the outer and inner solvents as well as the residual part. The molecular modeling of [Ni2(OBH)Cl4]·H2O·EtOH and [Co(OBH)2Cl]Cl·½EtOH are drawn and their molecular parameters proved that the presence of two metals stabilized the complex more than the mono metal. The complexes have variable activities against some bacteria and fungi. [Zr(OBH)Cl4]·2H2O has the highest activity. [Co(OBH)2Cl]Cl·½EtOH has more activity against Fusarium.ConclusionOxalo bis(2,3-butanedionehydrazone) structure was proved by X-ray crystallography. It coordinates with some transition metal ions as neutral bidentate; mononegative bidentate and neutral tetradentate. The complexes have tetrahedral, square-planar and/or octahedral structures. The VO2+ and Co2+ complexes have square-pyramid structure. [Cu(OBH)2Cl2]·2H2O and [Ni2(OBH)Cl4]·H2O·EtOH decomposed to their oxides while [VO(OBH–H)2]·H2O to vanadium. The energies obtained from molecular modeling calculation for [Ni2(OBH)Cl4]·H2O·EtOH are less than those for [Co(OBH)2Cl]Cl·½EtOH indicating the two metals stabilized the complex more than mono metal. The Co(II) complex is polar molecule while the Ni(II) is non-polar.Graphical abstractElectronic supplementary materialThe online version of this article (doi:10.1186/s13065-015-0135-y) contains supplementary material, which is available to authorized users.